To monitor a communication device (e.g., a switch, a router, a base station, or the like) that makes up a network, there are two methods: an out-of-band monitoring method; and an in-band monitoring method. The out-of-band monitoring method is used to monitor the communication device through a monitoring line not including the network as a monitoring target. On the other hand, the in-band monitoring method is used to monitor the communication device through the network as the monitoring target. When the communication device is located at a remote position and there is no out-of-band monitoring line, the in-band monitoring method is used.
To perform in-band monitoring (monitoring operation by the in-band monitoring method) on the communication device, an in-band monitoring VLAN (hereinafter referred to as a monitoring VLAN) is provided in the network. Each communication device is controlled on the monitoring VLAN. The control is performed by a Simple Network Management Protocol (SNMP), a Telecommunication Network (Telnet), a File Transfer Protocol (FTP), or the like.
The monitoring VLAN is made up of a layer-2 network. As for communication from a monitoring control device to the communication device, Quality of Service (QoS) may be set in a router on a route for each protocol type (SNMP, Telnet, or a port number of FTP).
However, priority control information may not be set to the communication (Ethernet (trademark) frame) from the communication device to the monitoring control device, so that the communication is performed with the same priority as other communication.
When connection type file transfer of configuration information or the like of the communication device is performed on the monitoring VLAN, a band of the monitoring VLAN may be occupied.
Japanese Laid-open Patent Publication No. Hei 11-136238 discloses a device that learns traffic characteristics of a signal channel in a packet network and that allocates bands.